This section introduces aspects that may be helpful to facilitating a better understanding of the inventions. Accordingly, the statements of this section are to be read in this light. The statements of this section are not to be understood as admissions about what is in the prior art or what is not in the prior art.
At microwave and millimeter-wave frequencies, a tunable high-Q filter is difficult to achieve in compact form due to either lack of suitable tunable element or difficulties in packaging the tuning mechanism into compact form.